An early morning line of showers and thunderstorms intensified during the afternoon upon encountering a favorable environment for severe thunderstorms. Steep mid-level lapse rates combined with strong instability.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MPX wrote it up.
An early morning line of showers and thunderstorms intensified during the afternoon upon encountering a favorable environment for severe thunderstorms. Steep mid-level lapse rates combined with strong instability. The storms produced damaging wind gusts which downed trees in several areas and mostly quarter to hen egg size hail, but some hail was much larger.
A hailstone in Stevens County measured six inches in diameter (it was photographed next to a ruler). This at least tied the record for the largest hailstone in Minnesota. Storm Data records also indicate six inch diameter hail in Nobles County on July 28, 1986, and in Murray County on July 4, 1968. The hail was collected about 13 to 15 minutes after the hail ended but was not saved in a freezer.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Twin Cities, MN wrote its last area forecast discussion before the first event at Jul 31, 12:19 PM CST, 1 minute earlier. Its key messages:
Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 119 PM CDT Wed Jul 31 2024 .KEY MESSAGES... - Some significant severe storms possible today, with uncertainty regarding timing and location. - Heat could approach heat advisory levels today, depending on evolution of storms and clouds. && .DISCUSSION... Issued at 332 AM CDT Wed Jul 31 2024 Warm and humid will be the story today, which will fuel some potentially significant severe storms across parts of the area this afternoon and evening. However, there remains quite a bit of uncertainty regarding storm activity later today as it could be heavily influenced by morning convection over South Dakota which models are struggling to resolve so far. CAMs solutions in particular are generally not picking up on the morning activity very well and therefore diverge quite a bit with storm evolution this afternoon. As the model spread suggests, the eventual evolution of morning storms could mean anything from storms/clouds making it as far east as the Twin Cities by mid afternoon, to storms not reaching western Minnesota until late afternoon and becoming more of an overnight threat for the metro and into Wisconsin. With this much uncertainty regarding storms and clouds, decided to hold off on any heat advisories for now until the picture can become more clear. If skies remain mostly sunny through the day, then temperatures could reach as high as the middle 90s and push heat index values as high as 105. Depending on how the convective picture eventually plays out later today, ingredients could line up for some potentially significant severe storms somewhere in the forecast area. Very strong instability coupled with rather steep mid-level lapse rates could favor damaging wind gusts greater than 70 mph as well as hail of 2" or larger. Shear will be marginal, so the most likely window for severe storms of this magnitude would be in the first couple of hours of storm initiation before strong outflow eventually weakens the overall line of storms. Once again where and when the strongest storms initiate will depend on how morning convection plays out, but the more likely scenario currently points to western and southwestern Minnesota for the strongest storms this afternoon with a weakening line approaching the Twin Cities by evening. If storms evolve faster than this, it could push the threat for severe storms further east toward the metro. We'll have a much clearer picture regarding today's thunderstorm and heat threats once models can better resolve this morning's convection out west. Thursday could see a few lingering showers and storms generally from the Twin Cities eastward as an upper level trough slowly drifts southeastward overhead. Instability and shear parameters will be generally unfavorable for strong storms with this activity. Things will then dry out for the weekend while temperatures rebound back into the upper 80s and lower 90s. Will need to watch for marginal heat concerns although dewpoints will be about 5 to 10 degrees lower than what we've seen the past few days. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 104 PM CDT Wed Jul 31 2024 The main concern through this evening will be the track and timing of a thunderstorm complex capable of damaging winds. Current radar has a cluster of severe storms along the central MN/SD border, and this complex is expected to impact AXN & STC over the next 1-3 hours. More uncertain is whether complex will build more to the south, and potentially bring severe thunderstorm impacts to RWF/MKT/MSP later this afternoon & early evening. Winds in excess of 40 kts are expected with these thunderstorms and potentially could gust as high as 70-80 kts. Current thinking is that we will see additional development tot he south of the ongoing complex, so have included a TEMPO for TSRA for 2-3 hours late this afternoon and early this evening. More uncertain is the potential for thunderstorms this evening behind the ongoing complex. The chance is lower wherever thunderstorms occur this afternoon, but become much more likely at RWF/MKT/MSP if the ongoing complex does not show any further development. For now, have handled this with a PROB30 mention but this will be upgraded or removed based on convective trends later this afternoon. After the precip tonight, MVFR ceilings are expected to develop early tomorrow morning & persist through much of the morning. KMSP...Very complex forecast regarding thunderstorms chances this afternoon & evening. The main window for thunderstorms and severe wind gusts currently looks to be between 5-8 PM. However, this depends on additional development occurring along the ongoing thunderstorm complex along the MN/SD border. If this development does not occur, a later round of thunderstorms (possibly severe) looks more possible, closer to 7-10 PM. Wind gusts over 40 kts are likely if the thunderstorm complex reaches MSP this evening with gusts around 70 kts possible. /OUTLOOK FOR KMSP/ THU PM...CHC MVFR -SHRA/-TSRA. Wind N 5-10 kts FRI...VFR. Wind NW 5-10 kts. SAT...VFR. Wind SW 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && DISCUSSION...DPH AVIATION...ETA
Hazardous Weather Outlook National Weather Service Twin Cities/Chanhassen MN 319 AM CDT Wed Jul 31 2024 MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028- 010830- Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns- Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa- Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington- Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota- Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth- Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk- St. Croix-Pierce-Dunn-Pepin-Eau Claire- 319 AM CDT Wed Jul 31 2024 This Hazardous Weather Outlook is for portions of central and southern Minnesota, and west central Wisconsin. .DAY ONE...Today and Tonight. Hot and humid conditions are expected today with heat indices approaching 95-100 degrees. Severe thunderstorms capable of damaging winds in excess of 70 MPH and large hail are likely this afternoon through this evening. The potential for destructive winds is highest across western Minnesota, but chances for severe weather still exist into eastern Minnesota and western Wisconsin. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... SKYWARN spotter activation may be needed.
Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
111 PM CDT Wed Jul 31 2024
MNZ054-055-311900-
Lac Qui Parle MN-Swift MN-
111 PM CDT Wed Jul 31 2024
...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN LAC QUI PARLE AND
WESTERN SWIFT COUNTIES THROUGH 200 PM CDT...
At 111 PM CDT, Doppler radar was tracking a strong thunderstorm near
Ortonville, moving east at 35 mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This strong thunderstorm will be near...
Lake Oliver around 140 PM CDT.
Other locations impacted by this storm include Louisburg, Big Stone
National Wildlife Refuge, Appleton Airport, and Holloway.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
A Severe Thunderstorm Watch remains in effect until 700 PM CDT for
west central Minnesota.
&&
LAT...LON 4527 9645 4525 9640 4525 9629 4522 9627
4519 9617 4520 9613 4518 9610 4541 9611
4541 9597 4521 9589 4509 9645
TIME...MOT...LOC 1811Z 254DEG 31KT 4525 9642
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
BorghoffThe Aberdeen radar (KABR), 175 km away, was scanning. The volume nearest the first event began at 18:21 UTC.
21 hail, 16 thunderstorm wind. Local standard time, as filed.
A few tree branches up to 4 inches in diameter were down.
Multiple trees were down along with power lines on roads.
Several dozen trees were downed or broken. A few landed on top of houses and sheds.
A hailstone measuring six inches in diameter was reported by a resident to emergency management. The hail next to a ruler were photographed. This at least tied the record for the largest hailstone in Minnesota. Storm Data records also indicate six inch diameter hail in Nobles County on July 28, 1986, and in Murray County on July 4, 1968. The hail was collected about 13 to 15 minutes after the hail ended but was not saved in a freezer.
A hailstone measuring six inches in diameter was reported by a resident to emergency management. The hail and ruler were photographed.
The hail was placed next to a quarter and photographed.
A large tree branch was down. A photo was provided.
Reported through mPing.
Reported via mPing.
Several trees and numerous large branches were down across Winthrop.
Multiple trees and branches up to 20 inches in diameter were down.
Trees were blown over or snapped.
A trained spotter reported numerous 3 inch diameter branches down as well as a 10 inch diameter pine tree that was uprooted.
Multiple large trees were blown down.
A radio antenna at the Goodhue Fire Department was damaged.
A large tree was blown onto a home in Bellechester.
A large pine tree was down on a power line.
Several trees and large branches were down.
A power pole was snapped.
Trees were down in Melville Township, near the intersection of Co Rd 3/Hwy 212.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2024Every state in 2024This day in weather historyWarnings in Minnesota, July 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1206060, 1206061, 1208896, 1205675, 1205654, 1206051, 1206055, 1205672, 1205671, 1206063, 1208677, 1208684, 1208687, 1206050, 1206076, 1205665, 1206049, 1206064, 1205660, 1206052, 1206077, 1205658, 1206071, 1206068, 1206078, 1206054, 1206079, 1206074, 1205677, 1205657, 1205676, 1205656, 1205653, 1208670, 1208671, 1206080, 1206059.